The present invention relates to a display device in a real image type viewfinder, and specifically to the display device in a viewfinder in which both an image of an object and a frame in a field of view can be observed.
Conventionally, various types of viewfinder systems have been proposed for a photographic camera and a video camera which have a photographic optical system and a viewfinder optical system. For example, as a simple viewfinder system, many viewfinder systems have been proposed, in which a lighting type viewfinder, an Albada type viewfinder, or the like is used. For example, in the lighting type viewfinder in these viewfinder systems, when a frame in a field of view has been displayed, the viewfinder has been composed of a frame made of other frame members through a half mirror.
Further, in the Albada type viewfinder, the viewfinder has been composed when the frame in a field of view, (hereinafter, called a view field frame), has been vaporized onto an eyepiece side member. Further, in the viewfinder system of a real image type, the viewfinder system has been composed as follows: a frame, made of other members, has been arranged near the position at which an image of the object has been formed using an objective lens, even when there is a display in the viewfinder.
In these cases, because a frame, for displaying the view field frame, and a space, in which the frame is supported, are necessary, the number of parts is increased, the display device becomes more complex, manufacturing processes become more complicated, and the manufacturing cost is increased. Further, because the view field frame is separate from the optical member, the position of the frame is shifted with respect to the image.
Further, as disclosed in Japanese Patent Publication Open to Public Inspection 183430/1988, the following has been proposed: the view field frame is displayed in the viewfinder using the shape of the prism on which processing has been conducted directly. Because the view field frame is formed when a V-shaped slot is cut in a Porro prism, it is difficult to precisely produce the end portion of the view field frame, and the processing cost is increased, so that the view field frame is not practical.